The present invention pertains to a dual durometer roller type guide member for use with upward-acting track guided garage doors and the like.
Upward-acting track guided sectional and one piece garage doors are typically supported and guided for movement between their closed and open positions by plural roller type guide members which are mounted on the door side edges and which engage and traverse along opposed guide tracks. Such guide tracks are typically formed as somewhat channel shaped members which are manufactured of formed metal plate. Moreover, conventional roller type guide members are characterized by formed metal rollers mounted on metal shafts. These metal on metal guide structures for upward-acting residential garage doors and other types of doors tend to generate a substantial amount of noise during opening and closing movement of the door and also on occasions when substantial and variable wind loads act on the door. Such roller guide member generated noise is objectionable in most door installations and it is desirable to eliminate such noise and to provide for long lasting, low friction, vibration free and quiet operation of such doors. It is to these ends that the present invention has been developed.
The present invention provides an improved track guided door including roller guide members which are quiet and reliable in operation.
In accordance with one important aspect of the invention, an upward-acting track guided door is provided with roller guide members disposed in opposed guide tracks and which guide members are each provided with an elastomer tire or tread, respectively, to provide quiet, reliable operation when the door is moved between open and closed positions and when the door may be subject to deflection due to wind loads and the like while in the closed position, in particular. The roller guide members are preferably formed of dual durometer plastic construction including a thermoplastic hub over which is molded a thermoplastic elastomer outer layer forming the so-called tread or tire portion which is of a softer or lower durometer than the hub portion. The roller guide members are preferably formed by a molding process wherein the hub is formed in a first molding step, the mold is expanded or modified and the tread portion is molded over the hub in a second molding step without removing the hub from the mold structure. A strong bond between the hub and the tread is formed in the molding process.
In accordance with a further aspect of the present invention, a dual durometer roller guide member is provided for use with track guided and upward-acting doors, in particular, and wherein the guide member is formed of dual durometer construction including a thermoplastic hub having a durometer of about Rockwell R120, for example, and a thermoplastic elastomer tread which is molded over the hub and is of a durometer of about 70 to 90 Shore A. The hub and tread are both, preferably, formed of a suitable urethane compound wherein the hub and the tread are strongly bonded together.
In accordance with a still further aspect of the present invention, a dual durometer roller guide member is provided for use, in particular, with track guided upward-acting doors and wherein the roller is provided with a low durometer thermoplastic elastomer tread of a configuration which assures quiet and reliable operation while minimizing drag or friction forces between the rollers and the guide tracks and also avoiding the rollers undergoing lateral oscillation or xe2x80x9cclimbingxe2x80x9d of the side walls of channel shaped guide tracks.
Those skilled in the art will further appreciate the above-mentioned advantages and superior features of the invention together with other important aspects thereof upon reading the detailed description which follows in conjunction with the drawing.